JP2964659B2 - Method of manufacturing current collecting electrode for laminated battery - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a collector electrode portion of a bipolar secondary battery, and more particularly to a press forming step (carbon plastic and metal mesh) which is a pre-step of injection molding as a framing step. Paste).

[0002]

2. Description of the Related Art Recently, the development of battery power storage systems has been promoted.
Chlorine batteries and redox flow batteries have been developed.
Among them, the zinc-bromine battery is a secondary battery that utilizes the oxidation-reduction reaction of zinc and bromine, has a normal temperature operation, an electrolyte circulation type structure, and is made of materials such as electrodes, separators, frames, piping, tanks, and the like. It is characterized by being mostly made of plastic. The voltage of the zinc-bromine battery is 1.8 V in open circuit voltage, and a high voltage can be obtained by adopting an electric series lamination structure. This battery employs a bipolar system, and is configured, for example, as shown in FIG.

In FIG. 3, reference numeral 6 denotes a separator plate in which an insulating frame is integrally formed on an outer periphery of a separator 11, and reference numeral 8 denotes a bipolar type in which an insulating frame is integrally formed on an outer periphery of a conductive member (electrode). Is an intermediate electrode plate. This intermediate electrode plate 8
Spacer mesh 7 on both sides with separator plate 6 in between
And the packing 5 are stacked to form a single cell. A plurality of the single cells, for example, 30 cells are stacked, and finally, at each end, a current collecting electrode (electrode end plate) 3, a stacked end plate 2, and a tightened end. The plates 1 are stacked and fastened with bolts and nuts to form an integral unit.

In the thus constructed battery body, the electrolyte is filled with the positive electrode manifold 9 and the negative electrode manifold 10 formed at the four corners of the intermediate electrode plate 8, the frame of the separator plate 6 and the packing 5, as well as the channel and the microchannel. Through the electrolytic solution flow path of the MC forming section 13 composed of

The conductive member (electrode) of the intermediate electrode plate 8 is formed of a carbon plastic thin plate formed by kneading a conductive material such as carbon with plastic, and the separator portion of the separator plate 6 is formed of a fine porous film. The frame of the intermediate electrode plate 8 and the separator plate 6 is made of a polyolefin resin such as polyethylene.

In the zinc-bromine battery constructed as described above, the positive electrode surface and the negative electrode surface are reversed on the surface and back surface of the electrode of the intermediate electrode plate 8. During battery operation (charge or discharge), the positive manifold 9 and the negative manifold 1
Since the electrolyte solution passes through the electrode surfaces of the positive electrode and the negative electrode through 0, the seal at the frame portion is an important point that determines the safety of the battery. Therefore, since high uniformity of the frame thickness is a necessary condition, the framing process of the intermediate electrode plate 8 and the separator plate 6 is performed by injection molding (thickness accuracy is limited in heat press molding).

However, since the current collecting electrode 3 has a large thickness because the metal mesh 4 for taking out current and a terminal are attached thereto, the framing step has also been performed by heat press molding. However, in the conventional current collector electrode heat press molding method, there is a limit in molding accuracy, and a hole punching step of the manifold is required as a post-processing. Therefore, injection molding has also been attempted for the current collector electrode.

That is, in the conventional injection molding method of a current collecting electrode, first, as shown in FIG.
33, a polyethylene sheet (GF; polyethylene sheet containing glass fiber) 34 is thermocompression-bonded to the member, and integrated to produce an insert (current-collecting electrode press-formed product) 35. Next, as shown in FIG.
And is molded by injecting the frame material 36. As described above, the conventional injection molding method of the current collecting electrode has been performed by two-stage molding of heat press molding and injection molding.

[0009]

However, the insert 3
5 and the frame member 36 are insufficiently fused, so that the electrolyte overflows through the interface between the insert 35 and the frame member 36 during use after being incorporated into the battery and comes into contact with the metal terminal attached to the back surface.
There have been cases of corroding this.

[0010] In order to increase the fusion strength between the insert 35 and the frame member 36, the rear side polyethylene sheet 34 used in heat press molding is replaced with the frame member 36 in injection molding.
It was tried to use the same material as. According to this, the fusion of the polyethylene sheet 34 and the frame member 36 on the back surface is good, but the carbon plastic flat plates 32, 33 on the side surfaces.
And the frame material 36 were not fused at all.

In the heat press molding, the compression temperature is 16
Since the temperature is 0 ° C. and the mold temperature in the injection molding is 40 ° C., the fusion between the carbon plastic flat plate 33 and the polyethylene sheet 34 is strong during heat press molding. However, at the time of injection molding, the frame material 36 is 26
Even if it enters at 0 ° C., it is cooled immediately, so that the fusion force is low.

In view of the above, it is an object of the present invention to provide a method for manufacturing a current collecting electrode of a laminated battery, which can increase the fusion strength between a heat press molded product and a frame material.

[0013]

SUMMARY OF THE INVENTION According to the present invention, a current collecting electrode is press-formed by sandwiching both surfaces of a current extraction metal mesh between a front side carbon plastic flat plate and a back side carbon plastic flat plate, and thermocompressing the member and a back insulating sheet. A method for manufacturing a current collecting electrode for a laminated battery, comprising: a heat press molding step of producing a product; and an injection molding step of injection molding a frame material into the current collecting electrode press molded product to produce a current collecting electrode injection molded product. In the heat press molding step, the outer dimension of the back side carbon plastic flat plate, or the outer dimension of the front and back side carbon plastic flat plate is set to be three times smaller than the outer dimension of the back insulating sheet.
~ 8 mm smaller, sandwiching a metal mesh between the front and back carbon plastic flat plates, and thermocompression bonding the member and the back insulating sheet to produce a current-collecting electrode press molded product. I have.

[0014]

The metal mesh for taking out the current, the front and back carbon plastic flat plates and the back insulating sheet are integrated by thermocompression bonding in a heat press molding step.
At this time, the outer dimensions of the back carbon plastic flat plate,
Or, the outer dimensions of the front and back carbon plastic flat plates are 3 to 8 mm larger than the outer dimensions of the back insulating sheet.
Because it is formed only small, the outer peripheral portion of the back insulating sheet covers the side surface of the carbon plastic flat plate. For this reason, when the frame material is injected in the injection molding process, the frame material and the heat press molded product are strongly fused not only on the back surface but also on the side surface of the carbon plastic flat plate.

[0015]

An embodiment of the present invention will be described below with reference to the drawings. In FIGS. 1 and 2, parts corresponding to FIGS. 4 and 5 described above are denoted by the same reference numerals,
A detailed description thereof will be omitted.

First, 5 mm of the outer circumference of the back carbon plastic flat plate 33 in the heat press molding step shown in FIG. 4 is shaved to form a back carbon plastic flat plate 51 as shown in FIG. Then, as in the case of FIG.
Are sandwiched between carbon plastic flat plates 32 and 51,
A polyethylene sheet 34 is thermocompression bonded to the member to be integrated. Then, the outer peripheral portion of the polyethylene sheet 34 wraps around the side surface of the back side carbon plastic flat plate 51, and the insert (current-collecting electrode press molded product) 52 as shown is manufactured. In this manner, the insert 52 is covered with the polyethylene sheet 34 not only on the back surface but also on the side surface of the back carbon plastic flat plate 51. Next, the insert 52 is fixed in the mold 41 in the same manner as in FIG. In this case, the frame member 36 and the insert 52 are strongly fused not only on the back surface but also on the side surface of the back carbon plastic flat plate 51. Therefore, when the completed current collecting electrode is used in a battery, the electrolyte does not overflow through the interface between the insert and the frame.

As a specific example, as a result of manufacturing under the following conditions, a current-collecting electrode press-formed product having a high fusion strength was completed. That is, the front side carbon plastic flat plate 32
Three carbon plastic sheets having a thickness of 0.6 mm (400 × 400), one sheet of a brass mesh 31 having current collecting terminals soldered thereto, and a back carbon plastic plate 51 having a thickness of 0.6 mm (390 × 400) 39
0), and the back polyethylene sheet 34 has a thickness of 0.6 mm (400 × 4).
00, polyethylene containing mica) and a polyethylene sheet containing glass fiber having a thickness of 1.0 mm (400 × 400) are successively stacked on each other (160 ° C., 50 kgf / c).
m ² , heat press for 5 minutes followed by cooling).

In the above-mentioned embodiment, the width of the outer periphery of the flat carbon plastic plate is reduced by 5 mm. When the shaving width is set to 2 mm, the shaving width is too small and the polyethylene sheet 34 does not wrap around the back side carbon plastic flat plate 51, which is also inconvenient. Therefore, the back side carbon plastic flat plate 5 whose outer peripheral width is smaller by 3 to 8 mm than a predetermined external dimension (mold dimension).
It is best to use 1.

As another embodiment for producing a current-collecting electrode press-formed product having a high fusion strength with the frame material, the outer periphery of the front carbon plastic flat plate 32 as well as the back carbon plastic flat plate 51 is formed by the flat plate 51. It may be cut by the same width as. In this manner, when heat press molding is performed, the outer periphery of the polyethylene sheet 34 wraps around the side surfaces of the back side carbon plastic flat plate 51 and the front side carbon plastic flat plate 32 as shown in an insert 53 in FIG. cover. For this reason, FIG.
When the current-collecting electrode press-formed product is injection-molded by the method shown in FIG. 5, the fusion strength with the frame member 36 is further increased.

In the above-mentioned embodiment, the case where the present invention is applied to a zinc-bromine battery is described.
It works.

[0021]

As described in detail above, according to the present invention, the outer dimensions of the back carbon plastic flat plate or the outer dimensions of the front and back carbon plastic flat plates are 3 to 8 mm smaller than the outer dimensions of the back insulating sheet. Since the heat press molding is performed by forming the frame small, the frame material and the heat press molded product can be strongly fused not only on the back surface but also on the side surface of the carbon plastic flat plate. For this reason, when the completed collector electrode is used in a battery, the electrolyte does not overflow through the interface between the heat-press molded product and the frame, maintaining safety and extending the life of the battery. Can be planned.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing one embodiment of a manufacturing method of the present invention.

FIG. 2 is an explanatory view showing another embodiment of the manufacturing method of the present invention.

FIG. 3 is an exploded perspective view showing a main part of a battery body of a zinc-bromine battery, which is one of conventional stacked batteries.

FIG. 4 is an explanatory view showing a conventional heat press molding step.

FIG. 5 is an explanatory view showing a conventional injection molding step.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 3 ... Collection electrode 4 ... Metal mesh 6 ... Separator plate 8 ... Intermediate electrode plate 13 ... MC formation part 31 ... Brass mesh 32 ... Front side carbon plastic flat plate 33, 51 ... Back side carbon plastic flat plate 34 ... Polyethylene sheet 35, 52, 53 ... insert 36 ... frame material 41 ... mold

Claims (1)

(57) [Claims] 1. A heat press forming step of sandwiching both sides of a metal mesh for current extraction between a front side carbon plastic flat plate and a back side carbon plastic flat plate, and thermocompressing the member and a back insulating sheet to produce a current collector electrode press formed product. In a method for manufacturing a current collecting electrode of a laminated battery, comprising: an injection molding step of producing a current collecting electrode injection molded article by injection molding a frame material on the current collecting electrode press molded article; The outer dimensions of the back carbon plastic flat plate or the outer dimensions of the front and back carbon plastic flat plates are formed to be smaller than the outer dimensions of the back insulating sheet by 3 to 8 mm, and the outer dimensions of the front and back carbon plastic flat plates are reduced. The metal mesh is sandwiched between the members, and the member and the back insulation sheet are thermocompressed and the current collecting electrode press A method for producing a current collecting electrode of a laminated battery, which is a step of producing a molded product.